The second MOST important shot in tennis.
Here is an explanation from Nikola Aracic of how to hit a return of serve. I like this explanation because he says a few things that I totally agree with. Most players are coached to step toward the serve or step in on the return. I find this to be false. You should be on your toes but your split step should send you in an up direction or side to side but not forward. I also like the 1/4 prep and 1/4 turn. Use the speed of the serve to your advantage. Too many big swingers miss-hit the serve because of their over rotation or their backswing is too big.
Let me know your thoughts.